1. Technical Field
The present disclosure relates to a foreign-object detecting device that detects a foreign object, such as metal and the human body (animal), for example, in the vicinity of a wireless electric-power transmitting device in a wireless electric-power transmission system. The present disclosure further relates to a wireless electric-power transmitting device and a wireless electric-power transmission system having such a foreign-object detecting device.
2. Description of the Related Art
In recent years, various types of mobile equipment, such as mobile phones, have been in widespread use, and the amounts of electric power consumed by the mobile equipment continue to increase because of improved functionality and performance and diversified content. When the amount of electric power consumed by mobile equipment that operates on a battery having a predetermined capacity increases, the operating time of the mobile equipment is reduced. As a technology for compensating for the limitation of the battery capacity, a wireless electric-power transmission system has been attracting attention. In the wireless electric-power transmission system, using electromagnetic induction between an electric-power transmission coil in a wireless electric-power transmitting device (also referred to as an “electric-power transmitting device”) and an electric-power reception coil in a wireless electric-power receiving device (also referred to as an “electric-power receiving device”), electric power is wirelessly transmitted from the electric-power transmitting device to the electric-power receiving device. In particular, in a wireless electric-power transmission system using a resonance-type electric-power transmission coil and electric-power reception coil, a high transmission efficiency can be maintained even when the position of the electric-power transmission coil and the position of the electric-power reception coil are displaced from each other. Thus, such a wireless electric-power transmission system is expected to be applied to various fields. In addition, the area in which charging is possible can be further increased by increasing the size of the electric-power transmission coil or configuring an array of a plurality of coils.
Related art is disclosed in, for example, Japanese Patent No. 4525710 (hereinafter referred to as “Patent Document 1”), Japanese Patent No. 4780447 (hereinafter referred to as “Patent Document 2”), and Japanese Unexamined Patent Application Publication No. 2011-234496 (hereinafter referred to as “Patent Document 3”).
In such related art, however, there are demands for a foreign-object detecting device that can detect a foreign object with high accuracy.